Throughout winter I go to an indoor pool regularly; I am not concerned with speed, just with endurance and cardiovascular fitness. Few weeks ago I was testing my new fins and since swimming in a pool with fins is a joke, decided to make it a little more challenging. I put on my weight belt with 9 lb of lead and started swimming on my back with scissor leg motion we all use under water. That proved surprisingly difficult -- I was completely winded after barely half the distance I normally swim, even as I covered that distance much faster than usual. After a few visits to the pool I figured out a workable stroke -- arms straight along the body with hands rigid, and move arms up and down in synch with legs, as if I were marching on my back. That way my hands add to the thrust of the fins. Still, it is HARD. Definitely more intensive exercise than just swiming, or swimming with fins only. Now, the time I can devote to the pool is somewhat limited -- if I am getting better heart workout from 30 minutes with fins and weight belt than from 45 minutes of breast stroke, I am all for it. But is that really the case?
Also, I wonder a little about the physics of fins. Everyone knows that with fins you swim faster, but I do not think they convert leg motion into forward momentum more efficiently -- rather, fins allow you to to apply more force with your legs. A fin pushes against more water than a bare foot does, so it propels more water backward, and in accordance with Newton's Third Law propels you forward faster. But exactly because you are pushing against more water, you must (given same up-down leg pace) apply more force. So the difference between swimming with fins and without is the same as the difference between pedaling a bike in 10th gear and in 1st gear -- given the SAME LEG PACE, you move much faster AND apply a lot more force. Which of course implies burning more calories and better heart workout.
Does that make sense, or am I missing something?
Also, I wonder a little about the physics of fins. Everyone knows that with fins you swim faster, but I do not think they convert leg motion into forward momentum more efficiently -- rather, fins allow you to to apply more force with your legs. A fin pushes against more water than a bare foot does, so it propels more water backward, and in accordance with Newton's Third Law propels you forward faster. But exactly because you are pushing against more water, you must (given same up-down leg pace) apply more force. So the difference between swimming with fins and without is the same as the difference between pedaling a bike in 10th gear and in 1st gear -- given the SAME LEG PACE, you move much faster AND apply a lot more force. Which of course implies burning more calories and better heart workout.
Does that make sense, or am I missing something?
